Valve tappet



Oct. 21, 1941.` f v. l. MoNcRlEr-'F 1 2,259,905

VALVE TAPPET I lFil-ed Marchl, 1940 2 Sheets-Sheel 1 INVENTOR ATTORNEYOct. 21, 1941.

v. l. MoNcRlEF'F VALVE TAPPET v Filed March v15, 1940 INVEN'VTQR .BY fve/@QM ATTORNEY Patented on. 21, 1941 UNI-Tao STATE s PATENT oil-FICEVcon I. Moncrieff, West Hartford, Conn., assignor to United AircraftCorporation, East Hartford, Conn., a corporation of DelawareAApplication March 15, 1940, Serial No. 324,165

(c1. 12a-9o) This invention relates to improvements in valve operatingmechanisms and has particular reference to an improved valve tappetincluding hyy draulic means for adjusting the operating mechanism toeliminate clearance between the diiferentv elements thereof. i y

An object of the invention resides in the provision of an improvedhydraulic adjusting mechanismfor a valve tappet in which the valveoperating forces transmitted through the tappet are not rried by thehydraulic uid used tov adjust the tappet but instead, are transmittedthrough metal screw threads of relatively' low pitch whereby the action,of the tappet itself is positive and the hydraulic iluid serves only toadjust the tappet to take up clearance in the valve actuating mechanism.

A further object resides in the provision of an improved valve operatingmechanism including an automatic tappet adjusting mechanism whichfunctions to maintain the valve operating mechanism tight at al1 timesduring operation but which is not capable of itselfy of exerting a forcein valve closing position.

` A still further object resides in the provision of an improvedhydraulic adjusting device for the operating gear of an engine valve soconstructed and' arranged that looseness or clearance in the valve gear1s gradually compensated during the initial period of engine operationand the adjustment is thereafter continuously -maintained during theoperating period rather than making a new adjustment for each operationof the valve gear. Y f

Other objects andl advantages will be morev particularly pointed outhereinafter orgwill become apparent as .the description proceeds.

, In the accompanying drawings, in [which like reference numerals' areused to designate similar parts throughout, there is illustratedv atypical which wouldopen the valve or tend to mainte-imu l the valveopenfwhen' the operating mechanism is gine and engine valve operatinggear showing the valve gear adjusting mechanism of the invention appliedthereto.

Fig. 2 is a. sectional view of a differentlfrag- 'mentary portion of anengine -showing Aan engine valve and the portion of the valve actuatingby conventional vconnecting rods or link-rods, not

illustrated. Arotatabl valve cam I6 is retained on the crankcasesurrounding or adjacent to the crankshaft Il by suitable means suchasthe bolt I8, ring 20 and spacer 22 and is driven from the crankshaft bysuitable means vincluding the gear teeth 2l. VIn a radial type ofinternal combustion engine, such as .that illustrated, the-valve cammember' i8 is in the form of a ring supported by abearing 26 on acrankcase offset and ceivesthe ball end of the (push rod 42. TheV enginevalve andvalv'e.l actuating mechanism and i an actuating mechanismadjusting device for substantially eliminating clearance 'between the'various elements of the valve activatingy mechanism duringengineoperatio". The'drawlss.

is provided with two` rows of valve operating cams sis/.indicated at 28and Il.l A tappet, generalLvy indicated at 32, is slidably mounted in atappet .guide ll secured in the crankcase III and 'is provided at itslower or inner end ,witha roller ,3B which rolls on the cams of the rowA28 and at its upper end with a socket member I8 which repush rod 42extends along the cylinder I2 and'at its upper end'is provided withaball element M,

l cularly illustrated in Fig. 2, which is receivedin a socket in one end:of a valve rocker arm l0 rotatably mounted intermediate its length onthe anti-friction bearingv secured in' the kerbox Il and carrying at itsopposite'end an adjustable socket l! which .receives'a ball 54 .bearingon the-upper end of the valve stem it.

- Thefvaiv'e stem!! hassecured upon the-upper however, are forthepurpose oi! illustration only l and are-not to be taken' as 4limitingthe inventionsince itwill be 'apparent to. those skilled in the art thatvarious changes in the illustrated .'constructionvmay vbe resorted towithoutin any way exceeding'the scope of the invention.

'the Vaccomllvani'ing drawings, Fig. 1 is a setional view of afragmentary portion of an Ien- 5l or outer end'rthereof a valve springretainer" I8 which cooperates with the .valve springs Si and I2 .to movethe valve stem through the guide M to v bring the head'- inizi-.gclodngrelation with the valve seat Il. The rocker arm Ill under actuation4ofthe` pushl rodf acts to compress'the springs and' l2 and move' thehead -ll ,away

'fromtheseat to open the valve, in s manner well known to the art. Whileonly one valve and valve operating mechanism has been illustrated,

it is well known that the conventional engine has a plurality ofcylinders, two or more valves for veach cylinder and an operating gearfor each parent" that whenever the roller 36 rides up on one of the camsin the row 28, as is particularly illustrated in Fig. 1, the tappet 82will be moved upwardly or outwardly in the guide :it and will move thepush rod d2 to rotate the rocker arm t8 about the bearing i8 and movethe plug 52 and ball 54 in a direction to force the valve stemdownwardly or inwardly through the guide Sli to compress the springs 80and 82 and open the valve, and when the roller rides down ofi of the camthe springs 80 and 62 will close the valve and force the push rod andvalve tappet downwardly or inwardly to ride on the inter-cam track ofthecam member it, in the position particularly illustrated in Fig. 3. l

As the engine operating temperature is considerably above thetemperature of the atmosphere and as the metal elements of the valveoperating gear have a natural coefdcient of heat expansion and thelength of the cylinders also changes because of the heat expansioncoelcient of the cylinder material and the change of temperature frominoperative to engine operating conditions` and as it is not alwayspossible to maintain the valve operating mechanism in exact adjustment,there is nearly always a certain amount of clearance or looseness in thevalve operating mechanism which will permit a certain amount of movementof the tappet 32 before the `valve begins tovopen. This clearance mayincrease or decrease as the engine warms up, the

tendency in the type of engine illustrated being for the clearance toincrease with temperature until it becomes relatively large, in vsomecases of the order of 0.060 of an inch. This large clearance occasionsanobjectionable amount of noise and cdnsderable unnecessary wear of thevalve parts and leakage of lubricating uid when the valve `actuatingmechanism is supplied with pressure lubrication from the engine. A largenumber ci devices have been suggested for autothe tappet guide. Thetappet is provided with a transverse channel 16 which connects with a.

longitudinal channel 18 which leads the oil past the tappet adjustingmechanism to a channel provided in the inner ball end 40 from which theoil ows through the hollow push rod and through channels in the upper orouter ball endv 48 and in the rocker arm 48 to lubricate the valveoperating mechanism all as particularly set forth in' United StatesPatent Number 2,123,681, issued July 12, 1938,' to Andrew V. D. Willgoosfor Internal combustion engine-rocker arm lubrication. As'isparticularly shown inFig. 1 and as is particularly set forth in thepatent above referred to, the ports 'I4 and 16 register only when theroller 36 is moved outwardly by one of the cams 28 so that the valveactuating mechanism and its ends are sealed by the walls of the tappetguide 34 and oil .under pressure is supplied from the port 14 throughAthe channel 8| and con-'- necting channel V82 to a longitudinal well orbore 84 provided in the tappet at the bottom of the larger bore 88 whichextends to the upper end of` the tappet. A check ball 88 is urged by acompression spring 90 to seat in the inner end of thevbore 84 to closethe channel 82 and prevent oil from owing out of the bore through thechannel. A reciprocable plunger 92 has a/hollow matically eliminatingthis clearanceduring engine operation but so far as applicant is awarethese .various prior art devices are subject to certain serious defects.and no one of them has,

up to the present, been put to any important commercial use.

It is to be understood that, while the improved automatic. adjustingmechanism for the valve operating gear' of an engine has been shown asapplied to a radial type of engine such asis or'- dinarily used for thepropulsion of aircraft, this actuating gear of any type of engine us/ingvalves.

actuated by slidable cam operated tappets.

In the improved construction, oil under pressure from the enginelubricating system is ledv lower end portion. 94 reciprocable in thebore 84 and a reduced upper end portion 98 passing through an apertureprovided in the socket 88 and into contact with the ball end 40. I'hesocket 38 is screw threaded into the open end of the bore 86, asindicated at 98, in such a manner that rotation of the socket relativeto' the tappet at |02 and |04. The end splines |02 are arranged parallelto the axis of the tubular member and cooperate with internal splines|08 provided inl the hollow'inner portion of the socket 38. -The splines|04v are spiral in form that is, arranged at an angle to the axis of thetubular member,

. and cooperate with corresponding spiral splines Varrangement is forconvenience in illustration .The screw threads 98 and the splines' |02and through the manifold 10 to the interiors of the various tappetguides B4 by means of drilled screw plugs 'l2 which provide'ports 14leading from |08 provided in the interior of the tappet 32 in termediatethe length of the bore 86.A The lower portion of the member |00y has asubstantially fluid tight t with the lower endA of'the bore 86.

|04 are so designed that an upward movement ofthe member |00 in the bore|08 toward the socket 38 will rotate the socket in a direction to screwit outwardly relative to theI tappet on the threads 98, and a movementof the member loo toward the bottom or the boro as will move the socket38`inwardly relative vto the tappet. While the socket may be moved'inwardly and outwardly relative to the tappet it is to be noted that theforce between the socket and the tappet for opening the valve is carriedby the screw thread 98 and not by the lubricating oil supplied throughthe channel 80. A compression spring 'disposed between an annularshoulder ||-2 on the plunger 92 and an internal flange III at the innerend of the member '|00 resliently urges the plunger 92 outwardly 'withrespect to" the member |00 and the tappet and maintains the upper 'endof the plunger in contact. with the adjacent., surface of tl ball end40. The hollow inner end 94 of the plunger 92 is provided with a valveseat surrounding an aperture H6 closed from the inside by a check ball||8 urged into seating relation over the aperture bya coil spring |20.Ports |22 lead from the interior of the hollow end 94 into the space inthe bottom of ber |00.

The operationof the device is 'substantially as aasaoos the innerportionof the' socket 38, from where it iiows through a clearance providedbetween thev plunger end 96 and the aperture in the socket 38 to the endof thechannel 80 in theball end l0.

the-purpose of disclosing the invention has been While a suitablemechanical embodiment for hereinabove described and illustrated i'n theaccompanying drawings, it is to be understood that the invention is notlimited'to the particular constructionso illustrated and describedbutthat such changes in the size, shape and arrangements of thevariousparts may be resorted to as come 1 the bore 86 below the end of thetubular memwhen the valve is closed and the valve is closed and theroller 38 is between cams, as illustrated in Fig. 3, the plunger 92 willbe forced upwardly by thespring H0 lifting the ball end Il!v 'out ofcontact with the socket 38, it being assumed that the member |00 is in apredetermined limiting Ainward position. If the engineis operating or fbegins to operate, as the roller 86 rides up on a cam 28 the tappet 32will be forced upwardly. As the strength of the spring ||0 is notsufficient to compress the valve springs 90 and 02, the

plunger 92 will be forced inwardly until the ball the surface of the endcomes in contact with socket 38. As the plunger is forced inwardly oilfrom the space in the wall 94 below the plunger the interior of thehollow end 9| forcing some oil contained in this 'hollow end out throughthe gradually pumping oil from the bore 94 into the space below themember |00I until the socket 38 has been `rotated outwardly on the screwthread 98a suicient amount to take up vthe clearance and discontinue thepumping action of the plunger. The oil pumped from thewell 84 by theplunger 92 is replenished each time the channel 80 comes'into registrywith the port 14 in 'the relative position of the parts illustrated linFig. 3. As long as the engine isoperating there i will be a constantvsupply of uid available to .m intain the member |00 in the properposition' to eliminate clearance in the valve actuating mechanism but assoon as the engine stops this iiuid will tend to gradually leak from themechanism and thespring ||0 will then force the member |00 inwardly ofthe bore 88 to its limiting inward position from which position it willautomatically start to move to eliminate clearance 'in valve actuatingmechanism vwhen the engine is again put into operation.

The oil for lubricating the'valve mechanism flows from the channel 19into the interior of the bore 86 beyond the portion which provideselement.

' will be forced through the aperture H0 and into valve to apply fluidpressure to said .abutment within the scope of the subjoined claims.

Having now described the invention so that y others skilled in the artmay clearly understand the same, what it isv desired to secure byLetters Patent is-as follows:

`l. An adjustable valve tappet comprising' a cam actuated reciprocableportion, an adjustable abutment screw threaded into one end oi' saidreciprocable portion on low pitch irreversible screw threads, iiuidpressure actuated means for rotating said abutment relative to saidreciprocable portion to adjust the length of said tappet; and meansoperative only when the lengthof said tappet is insuillcient forapplying fluid pres sure to said pressure actuated means.

2. An adjustable valve Atappet comprising, a hollow reciprocable member,an adjustable abutment screw threaded into one end of said reciprocablemember, a fluid pressure actuated element foradjusting said abutmentrelative to said reciprocable member, and a pump carried by saidreciprocable member `and having `an actuating portion extending throughsaid abutment for applying uid pressure to said pressure actuated 3. Inan engine valve actuating mechanism including a cam, and a ltappetmovable by said cam, means for automatically eliminating clearancebetween said tappet and the valve comprising, an abutment adjustablythreaded into said tappet, a iiuid pressure device carried by saidtappet for rotating said abutment to adjust the'y valve to apply fluidpressure to said abutmentl adjusting member. v

4. In an engine valve actuating mechanismincluding a cam, atappetmovable by said cam,

and a push rod movable by said tappet, means for automaticallyeliminating clearance between said tappet and said valve comprising, anabutment adjustably threaded into said tappet, a

fluid pressure actuated member for rotating said abutment to adjust 'thesame relative to said tappet, and a pump operative by relative movevment of said tappet andV said push rod when clearance exists betweenvsaid tappet and said adjusting member.

5. In avalve actuating mechanism including a cam, a tappet actuated bysaid cam, and means for transferring the movements of said tappet tosaid valve adjustable relative to said tappet to change the effectivelength of said tappet, means for `adjusting' the length of said tappetbetween said v`cam and said movement transferring meansI comprising,fluid pressure actuated means operatively connected with said movementtransthe fluid tight seal with the member |00 and then flows through thespline connections |00 and |02 to :ill the member |00 and thehollowinterior of ferring means for changing the effective length ofsaid tappet, and a pump operative only -when the length of said tappetis insufficient for applying fluid pressure to said pressure actuatedmeans. A

6. In a valve actuating mechanism including a cam, a tappet actuated'bysaid cam, means for transferring the movements of said tappet to said.

valve, and means for supplying lubricating oil toA said tappet, iluidpressure actuated means for adjusting the -eie'ctive length of saidtappet, and

' a pump connected with said lubricating oil suppy only at predeterminedpositions of said tappet operative only when the effective length ofsaid tappet is insufficient to apply iuid pressure to said pressureactuated means.

7. In a valve actuating mechanism including a cam, a tappet actuated bysaid cam, means for transferring the movements of said tappet to saidvalve, and means for supplying lubricating oil to said tappet, iuidpressure actuated means for adjusting the effective length of saidtappet, and a pump connected .with said lubricating oil supply only atpredetermined positions of said tappet operative only when the eiectivelength of said eratively connected with said valve, a tappet, and

a cam for moving said tappet, `means fonautomatically adjusting the,effective length of said tappet to'eliminate clearance in said valvegear comprising, an abutment for said push rod screw threaded into theouter end of said tappet, a uid pressure actuated element for turningsaid abutment on said screw 'threads to eliminate.' clear# ance in saidvalve gear, and a uid pump for applying uid pressure to saidpressureactuated element said pump'having an actuating plunger extending.through said abutment into contact with said push rod and a springacting on said stem to urge t said push rod away Vfrom said tappet saidspring having less strength than said valve spring whereby said pumpwill be operated during operation of said valve lgear .with c1ear ancebetween the parts thereof.

9 In a valve actuating mechanism including a cam, a tappet actuated bysaid cam, and means including a push rod for transferring the movementsof said tappet to said valve, means for adjusting the length of saidtappet between said cam and said push `rod comprising, fluid presload,and a pump operated by relative movement between said tappet and saidpush rod for applying uid pressure to said pressure actuated means. a rI VEQN I. MONCRIEFF.

